1. Technical Field
The present invention relates to a wearable apparatus for measuring position and action of an arm. More particularly, the present invention relates to a wearable apparatus that is worn on a user's arm for measuring a position and action of the arm and enables a robot to intuitionally learn necessary actions by precisely and stably measuring movement of the arm.
2. Description of the Related Art
As robots are used in various fields, the robots increasingly replace people for work. Various types of robots are used to repeatedly perform relatively simple and easy work or to work under severe environments that are difficult for people to work in. Further, robots mimicking humans are now used in industrial fields to perform work that humans have conventionally performed, such as automated production processes or dangerous probes. Accordingly, there have been various attempts to enable a user to intuitionally control motions of robots so that the motions are similar to human motions.
The simplest method is to directly input the positions of joint spaces or work spaces of a robot through a computer language or a touching pendant. This method requires designing in advance motion tracks of a robot intended by a user, numerically calculating tracks corresponding to the motion tracks in a work space or a joint space, and then inputting the values into an input device. According to this method, it is possible relatively easily estimate simple motions in the process of designing tracks, but when motions are complicated, an accident such as a collision may be caused due to misjudgment of the user, and additionally the user must learn robot motions by trial and error.
There is another method that transmits a 3D position and rotation information to a robot, using a 3D controller such as a 6-axis force sensor on the front of a robot. This method is to enable a user to give a robot instruction to move by holding and operating the 3D controller by hand. According to this method, however, when a robot having over six degrees of freedom is controlled, the position of an end effector can be moved as it is intended, but the robot may take undesired postures due to a redundant degree of freedom. Further, since all of motions of the robot are learned only through movement of the front of the robot, intuition of implementing a robot is somewhat poor.
In order to teach a robot having a redundant degree of freedom to make desired postures and motions, it may be possible to attach a torque sensor to every joint instead of a 6-axis sensor and make the robot take desired postures by applying force to the body in addition to the front of the robot. However, even in this case, there is a need for making paths by keeping intermediate points and smoothly connecting them, and it takes long time to make the robot learn complicated motions.
When a person learns a motion, he/she simulates a motion of another person. It is preferable that a robot can also recognize and copy motions of the human, but equipment that has been developed thus far has difficulty in precisely recognizing human motions. Motion capture devices that are usually used for making animations are classified into a type that visually recognizes markers on a body, a type that corrects signals from an inertia sensor using software, and a type that requires wearing a mechanical device, but none of them can measure human motions with high precision. Those motion capture devices are sufficient for making the overall motion of the human such as is required for animation purposes, but there is a need for an arm motion capture device that is very precise and stable relative to the motion capture devices.
An exoskeletal wearable device may relatively precisely measure motions in comparison to other devices, but it is complicated, and especially the shoulders of the human have a complicated structure of 7-degree of freedom, but at present it is difficult to design a mechanism for measuring even only three-directional rotation. FIG. 1 shows a 3-degree of freedom link assembly rotating about the rotational center of a shoulder and FIG. 2 shows a link mechanism with an additional degree of freedom for the back in the 3-degree of freedom link assembly. These assemblies are designed such that their shoulder centers are supposed to be aligned to the shoulder center of a person, but the shoulder makes complicated motions, so it is difficult to keep the rotational centers of the assemblies aligned to the rotational center of the shoulder, and accordingly, it may be inconvenient to move the shoulder due to corresponding resistance. Further, it is difficult to design a device that precisely measures forearm pronation/supination.